The present invention relates to self-leveling and grade setting construction lasers and is an improvement upon the prior art in that its novel use of thermal motors results in a laser leveling and grade setting system which is more rugged, more accurate, and more cost efficient than prior systems.
The prior art utilized rotary electric motors to level laser beam support structures after upset and to set variable pre-determined grades of the laser beam. The drive systems of such motors are complex and, since the minimum rotational speed of such motors must be relatively high to assure dependable starting operation, further complex means, such as fine thread screws, stepping, motors, or pulsing of the motor at low voltage, must be utilized to reduce the rotational speed of the laser on its pivot axis to an acceptable rate of approximately 60 arc-seconds per minute. These intricate motor systems are expensive, difficult to produce, and are of uncertain dependability and accuracy. Further inaccuracies are created by the inertia of a rotary motor's armature which can cause excessive oscillation of backlash in the beam positioning system.
The present invention by means of its novel use of thermal motors reduces the number of components in the motor system of a self-leveling and grade setting laser by approximately a factor of ten. Merely due to this reduction in the number of components, large production and maintenance cost savings are made possible. However, it is also true that thermal motors are inherently more rugged and dependable than rotary motors in the laser leveling and grade setting context and are therefore also more cost efficient on those grounds.
Far greater accuracy is also made possible by use in the present invention of thermal motors, which are practically free of backlash, and are free of inertia produced oscillation of the laser beam.
The present invention has the further advantage that it is easily adaptable to use in self-leveling and grade setting lasers presently being manufactured. This is due to the compactness of the thermal motors used in the present invention and their size compatibility with the structures used in presently manufactured lasers, as well as to the facility with which an embodiment of the present invention can be designed to match the impedence of existing electronic drives.